To allow faster operation, reduce cost and improve the power consumption of electronic devices, and in particular mobile electronic devices, integrated circuits are continuiglu being designed to operate on lower and lower voltages.
To minimise cost and avoid the need to redesign all elements within an electronic device integrated circuits are sometimes designed to include a regulator. This is to allow an integrated circuit that is arranged to operate on a first voltage to be coupled to a power supply operating at a higher second voltage. Consequently, this allows electronic devices to be upgraded with new integrated circuits without the need to replace the electronis devices existing power supply.
However, with the large range of different silicon technologies and associated operating voltages it can still be costly to have to design a range of different regulators, where different regulators are used with different integrated circuits and power supplies.
One way to avoid this problem has been via the use of programmable voltage supplies, where supply voltages are adjusted to provide a required voltage, one example of this technique is described in U.S. Pat. No. 5,790,469. However, this technique requires the use of an external voltage reference to allow the programmable voltage supply to determine an appropriate voltage, which yet again will typically result in an increase in complexity and cost of a device.
Further, as the operating voltage of integrated circuits continue to reduce it also becomes increasingly difficult to achieve the required voltage tolerances, for example a three percent tolerance on a one volt signal is a factor of ten less than a three percent tolerance on a ten volt signal.
For proper operation of an integrated circuit the voltage supply should ideally be monitored for variations of voltage outside the operating voltage range of the integrated circuit. Additionally, to avoid incorrect operation and possibly damage to an electronic module the monitoring circuit typically resets the integrated circuit on occations when voltage excursions occur outside the operating voltage range of the integrated circuit. However, for an electronic device with a new integrated circuit a monitoring circuit associated with the power supply will typically be unaware of the operating voltage range of the newly incorporated integrated circuit.
Further, as the testing of an integrated circuit will typically require operating the integrated circuit outside its normal operating voltage range any monitorint circuits will need to be disabled prior to testing to avoid the resetting of the integrated circuit. However, for safety related systems to include a mechanism to disable supply monitoring can be hazardous as it would be possible for the supply monitoring to be disable undesirably during normal operation.
Accordingly, it is desirable to improve this situation.